[FieldTrip] What exactly does 'minnbchan' refer just to spatial neighbors?

[David Groppe]

On Tue, Feb 8, 2011 at 11:01 AM, Eric Maris <e.maris at donders.ru.nl> wrote:
> Dear David,
>
>
>> Thanks very much for the email Eric, but I'm confused as to why you
>> answered "No" to my second comment.  From what I understand, if you
>> use a value of minnbchan that is greater than 0, then any significant
>> clusters will necessarily spread across multiple electrodes.  For
>> example, if you set minnbchan to 1, then all significant clusters will
>> have to include at least two electrodes so that each significant
>> "voxel" has at least one neighbor at another electrode.  Thus, if your
>> effect is truly at only a single electrode, having a value of
>> minnbchan greater than 0 will force you to miss the effect or to think
>> it occurs at more electrodes than it really does.  What part of my
>> reasoning is incorrect?
>
> Your reasoning is correct and mine was incorrect. I should read better
> before I write. My apologies for this.

Got it. Thanks very much for clarifying Eric.

>
> I do have to qualify that with minnbchan=0 it may also happen that your
> significant cluster contains more than one electrode (the electrode with the
> true effect plus some surrounding ones that by accident exceed the threshold
> that is used to identify clusters).

That makes perfect sense.  Since our lab uses only a limited number of
electrodes (32), I wanted to make sure I understood the minimum number
of electrodes an effect needs to span to be detected.
      once again, I very much appreciate your answers to my questions,
              -David

> Best,
>
> Eric
>
>
>
>
>>      again, thanks very much for the help,
>>             -David
>>
>>
>> > Best,
>> >
>> > Eric
>> >
>> >
>> > dr. Eric Maris
>> > Donders Institute for Brain, Cognition and Behavior
>> > Radboud University
>> > P.O. Box 9104
>> > 6500 HE Nijmegen
>> > The Netherlands
>> > T:+31 24 3612651
>> > Mobile: 06 39584581
>> > F:+31 24 3616066
>> > mailto:e.maris at donders.ru.nl
>> > http://www.nphyscog.com/
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >>     thanks for your help,
>> >>         -David
>> >>
>> >>
>> >> --
>> >> David Groppe, Ph.D.
>> >> dgroppe at cogsci.ucsd.edu
>> >> http://www.cogsci.ucsd.edu/~dgroppe/
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>>
>>
>>
>> --
>> David Groppe, Ph.D.
>> Postdoctoral Researcher
>> Kutaslab
>> Dept. of Cognitive Science
>> University of California, San Diego
>> http://www.cogsci.ucsd.edu/~dgroppe/
>>
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>
>
>
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-- 
David Groppe, Ph.D.
Postdoctoral Researcher
Kutaslab
Dept. of Cognitive Science
University of California, San Diego
http://www.cogsci.ucsd.edu/~dgroppe/